Former South Korean dictator Chun Doo-hwan was found guilty of defaming a dead priest on Monday, in connection with a pro-democracy uprising his troops crushed 40 years ago.

The 89-year-old dozed off as the verdict was read out in Gwangju, where the 1980 demonstrations ended in a bloodbath, but he was spared a return to prison.

The official toll for the dead or missing is around 200 people, but activists say it may have been three times as high, and Chun is known as the "Butcher of Gwangju".

He still denies any direct involvement in the suppression of the uprising, and in a 2017 memoir denounced a priest who had repeatedly testified that helicopter gunships had opened fire on civilians, as "Satan in a mask".

Under South Korean libel law defamation can be a criminal offence as well as a civil matter, relatives can file such complaints on behalf of dead people, and truth is not necessarily a defence.

The priest's family lodged a criminal libel complaint against Chun and prosecutors took him to trial.

Protesters held pictures of an effigy of former South Korean President Chun Doo-hwan outside a court in Gwangju where his defamation trial took place
Protesters held pictures of an effigy of former South Korean President Chun Doo-hwan outside a court in Gwangju where his defamation trial took place AFP / Jung Yeon-je

"Chun was aware of the helicopter shots fired," the court said, adding Chun alone bore the "main responsibility" for the casualties.

It gave him an eight-month suspended sentence, well short of the 18-month custodial term sought by prosecutors, with Yonhap news agency quoting the judge as calling on him to "sincerely atone" for his deeds.

Wearing a facemask and a black hat, Chun -- who was not held in custody during the trial -- did not speak to reporters as he left.

Chun governed South Korea with an iron fist during the 1980s. He oversaw the country's economic rise and won the right to host the 1988 Summer Olympics, but also brutally repressed opponents until mass demonstrations forced him to accept democracy.

He was the country's first president to hand over power peacefully, but remains among its most reviled figures.

In 1996, he was convicted of treason and condemned to death, in part over what happened at Gwangju, but his execution was commuted on appeal and he was released following a presidential pardon.

All four of South Korea's living ex-presidents are either currently in prison or have previously served jail terms.

South Korea